JPH0376188B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a roll coater type coating device for coating a strip-shaped object. This invention is applied to coating steel plates and other strips.

(Prior Art) Generally, a roll coater type coating device is widely used for continuous coating of a strip-shaped object such as a steel plate.

As such a roll coater type painting device,
For example, there is a coating device disclosed in Japanese Patent Publication No. 60-56552. As shown in FIG. 2, this coating device consists of a back-up roll 1 on which a strip S is wound, a pick-up roll 2 whose lower part is dipped in paint in a paint pan 9, and a pick-up roll with a required gap. 2 and is provided with an applicator roll 3 that is in contact with the strip S. Then, the paint from the paint pan 9 adheres to the rotating pick-up roll 2, and the adhered paint passes through the applicator roll 3 and is applied to the strip S wound around the back-up roll 1.

Another example is the coating device disclosed on page 347 of Latest Coating Technology (Expanded Edition) (Supervised by Yuji Harasaki, Published by General Technology Center). As shown in Fig. 3, this coating device includes a back-up roll 1, a dual-purpose roll 8, and a doctor roll 5
and a blade 6. The dual-purpose roll 8 deposits the paint in the paint pan 9 and supplies it to the surface of the strip. The doctor roll 5 adjusts the thickness of the paint adhering to the dual-purpose roll 8, and the blade 6 scrapes off the paint adhering to the doctor roll 5.

(Problems to be solved by the invention) In the coating device of the above-mentioned Japanese Patent Publication No. 60-56552,
The pick-up roll and applicator roll have what is called a natural rotation. That is, both rolls are rotating in opposite directions, and at the position where the circumferential surfaces of both rolls meet, both circumferential surfaces are moving in the same direction. As a result, gearbitation and filamentation occur in the exit region of the roll gap between both rolls, causing foaming and threading due to air intrusion. This threading phenomenon causes streak-like unevenness in the paint adhering to the surface of the applicator roll, and the unevenness is transferred to the coating surface of the strip, impairing the smoothness of the coating surface. Further, in order to prevent the above-mentioned unevenness, the circumferential speeds of the pick-up roll and the applicator roll and the range of adjustment of the roll gap between the pick-up roll and the applicator roll are limited.

Furthermore, in the coating apparatus described in the above-mentioned document, when the dry coating thickness exceeds about 10 μm, the smoothness of the coating surface is impaired as described above. In addition, when applying thick coatings, there are two methods: widening the roll gap between the applicator roll and pick-up roll, and increasing the circumferential speed of the applicator roll. With this method, the effect of eliminating bubbles in the paint is reduced, so defects such as dents due to bubbles are likely to occur in the coating film. In this method, paint scatters, and since the peripheral speed of the pick-up roll is increased, the pick-up properties of the pick-up roll deteriorate, and coating film defects are likely to occur due to insufficient supply of paint.

This invention aims to prevent the deterioration of the smoothness of the coating film surface, coating defects caused by bubbles, and paint scattering in conventional roll coater type painting equipment, and to improve the pick-up properties of the paint.

(Means for Solving the Problems) The roll coater type coating device of the present invention is arranged to provide a transfer film located downstream of the pick-up roll in the rotational direction of the applicator roll, and adjacent to the applicator roll with a required gap. It is equipped with an arrow roll, a doctor roll that is close to the transfer roll with a required gap, and a blade whose cutting edge is in contact with the doctor roll.
The back up roll, applicator roll, transfer roll, and doctor roll are all driven to rotate in the same direction, and the pick up roll is driven to rotate in the opposite direction to these rolls.

(Function) A portion of the paint that has adhered to the applicator roll from the pick-up roll adheres to the transfer roll on the upstream side in the rotational direction of the applicator roll, and the rest rotates and moves with the applicator roll as it is. The paint on the transfer roll moves as the roll rotates, and overlaps the paint on the applicator roll at a position on the downstream side where the applicator roll and the transfer roll meet. The overlapping paint is then deposited on the strip on the back-up roll. Note that the coating film thickness is adjusted by adjusting the circumferential speed of each roll and the roll gap between each roll.

Since the back up roll, applicator roll, transfer roll and doctor roll all rotate in the same direction, unevenness on the paint surface is eliminated. Furthermore, since the paint is applied to the strip in an overlapping manner, the roll gap between each roll can be reduced, and the generation of bubbles and paint scattering are prevented. Furthermore, when painting with a predetermined film thickness, there is no possibility that the pick-up properties of the paint deteriorate, resulting in a shortage of paint supply and resulting in a poor painted appearance.

(Embodiment) FIG. 1 shows an embodiment of the present invention, and is a configuration diagram of a roll coater type coating apparatus.

As shown in the drawing, the coating apparatus is equipped with five rolls: a back-up roll 1, a pick-up roll 2, an applicator roll 3, a transfer roll 4, and a doctor roll 5.

A steel plate S to be painted is wrapped around the back-up roll 1. A payoff reel for feeding out the steel plate S is disposed on the upstream side of the backup roll 1, and a tension reel (both not shown) for winding up the steel plate S is disposed on the downstream side. The pick-up roll 2 is arranged so that its lower part is immersed in the paint in the paint pan 9. The applicator roll 3 is placed with a required gap between it and the pick-up roll 2 and is in contact with the steel plate S. The transfer roll 4 is located downstream of the pick-up roll 2 with respect to the rotating direction of the applicator roll 3, and is arranged so as to leave a required gap in the applicator roll 3. The doctor roll 5 is arranged so as to leave a required gap with the transfer roll 4. Further, the coating device includes a blade 6 whose cutting edge is in contact with the doctor roll 5. The blade 6 extends along the width direction of the doctor roll 5 and scrapes off paint adhering to the surface of the doctor roll 5.

The back up roll 1, applicator roll 3, transfer roll 4 and doctor roll 5 are all driven to rotate in the same direction, and the pick up roll 2 is driven to rotate in the opposite direction to these rolls by an electric motor (not shown). Further, the applicator roll 3, transfer roll 4, and doctor roll 5 are rotatably supported on a horizontally movable bearing stand (not shown). The roll gap between each roll is adjusted by displacing the bearing stand.

In the coating apparatus configured as described above, the pick-up roll 2 attaches the paint in the paint pan,
The adhered paint is transferred to the applicator roll 3. A part of the paint adhering to the applicator roll 3 from the pick-up roll 2 adheres to the transfer roll 4 on the upstream side with respect to the rotating direction of the applicator roll, and the rest rotates and moves with the applicator roll 3 as it is. The paint on the transfer roll 4 moves as the roll rotates, and overlaps the paint on the applicator roll 3 at a position on the downstream side where both rolls meet. The overlapping paints are then adhered to the steel plate S on the backup roll 1. The coating film thickness is adjusted by adjusting the circumferential speed of each roll and the roll gap between each roll.

Here, an example of coating by the above-mentioned coating apparatus will be explained.

The coating conditions were as follows.

Paint viscosity: 50-140 seconds Food cup #4 Paint solid content: 25-50% Line speed: 40 m/min Roll peripheral speed ratio Pick-up roll: 0.5-0.7 Applicator roll: 1.1-1.6 Transfer roll: 1.1-1.6 Doctor roll 5 :0.1~0.8 Roll gap (mm) Pickup/Applicator: 0.3~0.5 Applicator/Transfer: 0~-0.3 Transfer/Doctor: 0~-0.3 Backup/Applicator: -0.3 Dry film thickness: 0.5~40μm Above As a result of coating under the coating conditions, a smooth product with no surface defects was obtained.

(Effects of the Invention) According to the roll coater type painting apparatus of the present invention, it is possible to obtain a product with excellent coating film surface smoothness and no coating film defects. In addition, since scattering of the paint is prevented and the pick-up properties of the paint are improved, it is now possible to paint a thick film without damaging the coated surface.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of a conventional roll coater type coating apparatus. 1...Backup roll, 2...Pickup roll, 3...Applicator roll, 4...Transfer roll, 5...Doctor roll, 6...Blade,
8...Dual use roll, 9...Paint pan.

Claims (1)

[Claims] 1. A back-up roll around which a strip to be painted is wrapped, a pick-up roll whose lower part is dipped in paint in a paint pan, and an applicator roll that approaches the pick-up roll with a required gap and is in contact with the strip. and a transfer roll located downstream of the pick-up roll in the rotational direction of the applicator roll and adjacent to the pick-up roll with a required gap between the applicator roll and a transfer roll with a required gap between the transfer rolls. It is equipped with an adjacent doctor roll and a blade whose cutting edge contacts the doctor roll, and the back-up roll, applicator roll, transfer roll, and doctor roll are all rotated in the same direction, and the pick-up roll is rotated in the opposite direction from these rolls. A roll coater type painting device characterized by being rotationally driven.